An eye surgery microscopy system is required for cataract surgery. The eye surgery microscopy system is used here for magnifying visualization of the surgical region. During the cataract surgery, the natural lens of a patient eye in which a cataract has developed is replaced with an artificial lens, a so-called intraocular lens. An opening in the lens capsule is prepared via an incision through the sclera or cornea within the inner edge of the iris. The natural lens is then smashed through this opening with an ultrasound device and later removed. After the removal of the natural lens, the intraocular lens is introduced through the opening in the lens capsule of the patient eye.
An eye surgery microscopy system of the type referred to above is known from US 2006/0247659 A1. There, an ophthalmologic surgical microscope is described which has a pattern generator. With the pattern generator, a marking pattern can be superposed onto the viewed image in the surgical microscope which serves as an orientation aid during surgery on a patient eye, for example, in the so-called cataract surgery. The pattern generator is connected to a unit for the determination of the pupil position of the patient eye and this unit has an image sensor with a computer unit.
In eye surgery, intraocular lenses having spherical, aspherical, multifocal and even toric geometries are used.
In toric intraocular lenses, it is necessary that the axis of the torus of the intraocular lens is aligned in a defined manner in the patient eye during the cataract surgery to compensate for vision defects of the patient.
It is known to apply in advance of the surgery on the patient eye, as a rule, two mutually opposite dot-shaped markings at the edge of the limbus with a tincture tolerated by the patient. These markings serve as a reference for the surgeon. During surgery, a video image of the patient is generated on which these markings are visible. After introducing the toric intraocular lens into the patient eye, the toric intraocular lens is aligned while using a template guided on the image screen. This template is moved by an assistant in front of the display screen corresponding to markings which are visible on the video image of the patient eye.
It is further known, in addition to applying reference markings to the patient eye, to additionally prepare on the patient eye also a marking for the target position of the toric intraocular lens. This, however, makes an additional marking step necessary.
The image of the object region, which a surgeon sees in a cataract surgery, is not stationary. On the one hand, the patient eye can shift during surgery, notwithstanding a local anesthesia. On the other hand, mechanical vibrations of eye surgery microscopy systems cannot be completely prevented. The microscopy systems are, as a rule, held with an adjustable stand unit above the head of the patient undergoing surgery. These vibrations become disturbingly noticeable during the imaging of an object region and primarily at higher magnifications. A highly movable image of the object region makes an alignment of a toric intraocular lens especially difficult when using a template guided in front of the video display screen.